isPointerPanZoomAllowed method Null safety
- PointerPanZoomStartEvent event
protected">@protected
    Checks whether or not a pointer pan/zoom is allowed to be tracked by this recognizer.
Implementation
@protected
bool isPointerPanZoomAllowed(PointerPanZoomStartEvent event) {
  return _supportedDevices == null || _supportedDevices!.contains(event.kind);
}